4. Description: Adenosine is a kind of endogenous nucleoside distributed throughout human cells, which can directly enter the myocardium through phosphorylation to produce Adenosine, and participate in the myocardial energy metabolism, as well as the expansion of coronary arteries and the increase of blood flow. Adenosine on the cardiovascular system, and many other systems of the body and the organization has the physiological functions, with broad heart effect, is approved by the FDA converting paroxysmal room sex on the room tachycardia (PSVT) first-line drugs, heart drug is approved by the FDA for load test of one of the two drugs, has become a quickening the emergency treatment of arrhythmia and drug load test of conventional drugs, with negative chronotropic and inotropic, variable transmission and fast significant coronary artery expansion effect, but also has triggered or mediated ischemia preconditioning, reducing reperfusion injury such as cardiac protection effect. Adenosine is also an important intermediate for the synthesis of adenosine triphosphate (ATP), adenine, adenosine and adenosine.